It is a fair question to ask what line of work this is for.
When I was office temping I was given a very rudimentary English test. More about usage (correct usage of there, their, they're) for example and less about spelling.
Whereas a friend who was going for what was basically a copy editing/proof reading job had to sit a far more vigorous test where your concerns would be quite valid.

If you do suspect that you will end up with the latter kind of test then ask for a copy of the house style guide. This will tell you exactly what you need to know.

Wot Zoe sed .

+ 1 too, to the "be consistent" advice; both US & UK spelling is acceptable here. I've learned (or learnt) over the years to write/edit "for my audience". This sometimes involves going over to the Dark Side & AmericaniZing ! Depends on the job, IMO. I have, however, never manage to bring myself to use "gotten" ... .

And if they haven't got a clue what you are on about, this tells you an awful lot as well... and if they do, showing awareness of what they are gets your foot in the door nicely. Better yet, if you've had to use one in anger (but you're in to prior experience there, and it maybe tricky to bluff this one).

If you're interested in this kind of thing, the Economist Style Guide is a great start. There's also a Canadian Press Style Guide - but from what I understand these days, you're only talking about old school print journos that will really be tight on that. A former colleague had her own copy, and it's a much weightier and more expensive tome than the Economist one!

Also, there *is* an Oxford Dictionary of Canadian English. In my experience, hardly anyone seems to have even heard of it, let alone adhere to it...

Not exactly. Mostly the same. In the case of s vs z they go with the yanks though. And for the clueless I'm talking about CiviliSed vs CiviliZed

How very Canadian of you.

No it's to let Canadians know they should laugh.

Just after I moved over here at the back end of 2013, I was tasked by my employer to proof read a large tender submission for part of a (now on hold) big waste water treatment project on Vancouver Island.

As part of my review, I converted the entire document to English English, including terminology, alternative spellings and different words, much to the disgust of our Submissions team.

Much discussion followed and I was deemed to have done the right thing, the original drafts having been in mixed English and American English, due to having been produced by about six companies in our bid consortium.

We got through to the next bid stage, so I must have dome something right

Then the project got shelved.